1. Field of the Invention
The present invention relates generally to in situ measurement of fluid density and flow rate in pipe; and it relates specifically to methods and apparatus for measuring dynamic fluid level and load (weight) in a region of pipe and correlating these measurements of the fluid with a density and flow rate—with particular applications to return drilling fluid/mud.
2. Background of the Related Art
Drilling fluid, also known as “drilling mud,” is used to: (1) remove cuttings from a formation produced by a drill bit at the bottom of a wellbore and carry them to the surface; (2) lubricate and cool the drill bit during operation; and (3) maintain hydrostatic equilibrium so that fluids and gas from the formation do not enter the wellbore in an uncontrolled manner causing the well to flow, kick or blow out. In all such roles, but particularly the latter one, a knowledge of the density and flow rate of the drilling fluid is critical.
Current methods to measure flow rate of a return drilling fluid typically involve inference from the initial pump rate—precluding the ability to monitor the flow rate differential between the initial and return fluid. Moreover, current methods for measuring return drilling fluid density are typically indirect, ex situ techniques. See, e.g., American Petroleum Institute (API) Recommended Practices 13B-1, and 13B-2.
In view of the foregoing, an improved method for accurately and efficiently measuring such above-described fluid flow parameters in situ would be highly beneficial, particularly with regard to return drilling fluid.